The invention relates to an aerosol for dispensing a liquid, in particular in the form of a foam, at least comprising a liquid container and a dispensing assembly which is coupled thereto at least in liquid-tight manner, the dispensing assembly comprising a liquid pump with a liquid inlet and a liquid outlet, and an actuating head, the actuating head comprising an outlet passage and a dispensing opening for dispensing the liquid, while the actuating head furthermore comprises a closed, circumferential protective cap, the aerosol comprising a circumferential recess, into which the protective cap can move, which recess comprises a closed inner wall, an outer wall and a base, and one or more outlet openings are present in the vicinity of the base of the recess.
An aerosol of the type referred to above is known from JP-A-9-77115.
Aerosols of the type referred to in the introduction are used, inter alia, to dispense liquids as such, such as toothpaste, gel, etc. There are also aerosols which are intended to dispense atomized air/liquid mixtures, such as deodorant, hair sprays, paint, etc. However, the latter type of aerosol may also comprise foam-forming means, so that the aerosol is suitable for dispensing foam products, such as shaving foam, soap, shower foam, etc.
In the context of the present invention, the term liquid is understood as meaning both low-viscosity liquids and viscous liquids and pasty materials.
In the aerosol described in JP-A-9-77115 the inner wall of the annular recess forms a substantially vertical guide wall for the protective cap. In other words, during use, the protective cap moves up and down along this inner wall in very close proximity thereto.
In the case of personal hygiene products, the aerosol is frequently used in a damp environment, such as in a bathroom in the bath or under the shower. In the case of paint and other products, it is also necessary to prevent liquid products, such as the products to be dispensed or water, entering the dispensing assembly.
The aerosol described in JP-A-9-77115 is reasonably successful at preventing water which runs downwards along the protective cap, for example, finding it easy to enter the dispensing assembly at the liquid pump.
When the aerosol is used, by depressing the actuating head, a liquid will be dispensed by actuation of the liquid pump and emptying of the liquid pump chamber. If the actuating head is then released, the pump will move back towards its starting position, during which movement the pump chamber is filled with liquid. While the pump chamber is being filled, liquid is withdrawn from the liquid container. This volume of liquid which has been removed has to be compensated for by admitting air to the liquid container from the protective cap.
When the actuating head is depressed, the space which is enclosed by the actuating head and the inner wall of the annular recess will be reduced in size. When the actuating head moves back into its starting position, this volume will increase in size. This also has to be compensated for by admitting air.
In both cases, air will be drawn into the dispensing assembly between the inner wall of the annular recess and the protective cap. It is thus nevertheless possible for leakage water, possibly contaminated with dispensed liquid, conceivably in the form of a foam, to enter the dispensing assembly.
Products which are to be dispensed using aerosols are frequently sticky once they have dried and therefore, if they reach the dispensing assembly, can considerably impede and even completely disrupt operation thereof.
It is also the case that the liquids to be dispensed are frequently liquids which give rise to the formation of foam, with all the associated disadvantages.
It will be clear that it is also highly undesirable if there is any possibility of foreign substances from the environment entering the liquid container together with the leakage water.
The object of the present invention is to provide a solution to the above problems.
The present invention provides for an aerosol for dispensing a liquid, in particular in the form of a foam, at least comprising a liquid container and a dispensing assembly which is coupled thereto at least in liquid-tight manner, the dispensing assembly comprising a liquid pump with a liquid inlet and a liquid outlet, and an actuating head, the actuating head comprising an outlet passage and a dispensing opening for.dispensing the liquid, while the actuating head furthermore comprises a closed, circumferential protective cap, the aerosol furthermore comprising a circumferential recess, into which the protective cap can move, which recess comprises a closed inner wall, an outer wall and a base, and one or more outlet openings are present in the vicinity of the base of the recess, characterized in that the shape of the recess is such that the inner wall, on the side which is remote from the base, is at a radial distance p from the protective cap, which distance p is greater than the usual clearance distance of the protective cap with respect to the inner wall.
Due to the particular shape of the inner wall of the recess in the aerosol according to the invention, any liquid which is sucked up during the restoring movement of the dispensing head can be temporarily accommodated in the space between the inner wall which is of particular design and the protective cap. Once the restoring movement has been completed, at the latest, the liquid can easily flow out of this space to the outlet openings or can be pressed out during a subsequent actuation.
The particular design of the aerosol according to the invention makes it virtually impossible for water to enter the dispensing assembly from outside the aerosol. All the leakage water will be discharged through the outlet opening(s) in the base of the recess to the environment.
The available clearance distance is understood as meaning a distance p as disclosed, for example, in JP-A-9-77115. This distance p is such that there is suitable guidance provided between the inner wall of the recess and the protective cap, and will in practice be relatively small. This distance p will be selected in such a manner that the protective cap can be successfully guided by the inner wall without unnecessary friction.
Advantageously, the distance p according to the invention is at least 2 mm, or the distance p is greater than or equal to 0.1 times the internal diameter d of the protective cap. The distance p is preferably greater than or equal to 0.3 times the internal diameter of the protective cap, and more preferably greater than or equal to 0.5 times the internal diameter of the protective cap. It will be clear that the distance p is most preferably as great as possible.
According to the invention, various shapes of the inner wall are possible. For example, this inner wall may comprise a substantially straight cylinder with a diameter which is significantly smaller than the internal diameter d of the protective cap, the distance p between the straight cylinder and the inside of the protective cap being greater than the available clearance distance as defined above. In this embodiment, it will be impossible for any liquid to be sucked up, since the distance between the inner wall and the protective cape is too great.
Preferably, however, the inner wall of the recess, at least in the vicinity of the side which is remote from the base of the recess, is of conical shape which widens towards the base. Particularly in the latter design, which will be explained in more detail below in the figure, the conical shape of the inner wall will prevent any formation of bubbles in the space between the inner wall and the protective cap. Bubbles which form in that area will be easy to break up due to the increase in their surface area which occurs.
The basis of the present invention is that there is no liquid sucked up between the inner wall of the recess and the protective cap, or that a space is formed between the inner wall and the protective cap, in which any liquid which is sucked up can be temporarily stored and then discharged. These aspects will be explained in more detail below in the description of the figures.
Preferably, the dispensing assembly furthermore comprises an air pump with an air inlet and an air outlet. The present invention offers particular advantages if there is an air pump present. When the air pump chamber has been emptied, for example after an atomized liquid or a foam has been dispensed, this chamber has to be refilled with air from the environment. If, at that moment, water is present in the dispensing assembly, there is a high risk of it being sucked into the air pump chamber via the air inlet. Not only does this impede the operation of the air pump, it also disrupts the mixing ratio between the air and liquid. The mixing ratio is of essential import for many air/liquid mixtures which are to be dispensed. In practice, this applies in particular to so-called foam formers.
A foam former is an aerosol which comprises foam-forming means. Foam-forming means are, for example, one or more small meshes in the outlet passage. A foam is formed by mixing air and liquid and then passing it through the meshes. If additional leakage water, for example, is mixed with the air and the liquid, in the most serious case there will be no foam formed at all.
The outlet opening(s) in the base of the recess may, if necessary, be in communication with outlet means which guide the water to outside the aerosol.
In a particular embodiment of the aerosol according to the invention, the air pump and the liquid pump are designed as an assembly of two concentric piston pumps. Particularly with concentric piston pumps of this nature, it is imperative that any leakage of water into the dispensing assembly in the vicinity of the pumps be avoided. All this will be explained in more detail below in the description of the figures.
Advantageously, the internal diameter of the protective cap of the actuating head is greater than the external diameter of the piston pumps which are present. In this way, the pumps are very well protected against the penetration of water.
Preferably, the recess according to the invention forms a part of the dispensing assembly.
The invention furthermore provides a dispensing assembly which is intended for an aerosol according to the invention.
The invention will be explained in more detail below with reference to the appended drawing.